The present invention relates to the field of machine recognition of magnetically printed characters on a document, and more particularly to a document reader system in which a multiple-gap magnetic read head is used in reading magnetized characters embodied in the form of E-13B character font printed on a document.
In single-gap magnetic character reading systems, a single analog input waveform is obtained by passing the characters to be sensed, normally printed on a document, beneath a magnetic read head at least as wide as the height of the characters and having a single flux gap. The signal generated by the read head is a derivative waveform representing the rate of change of magnetic flux transversing the head as the characters are scanned. Since the distribution of ink, and thus flux, associated with each different character is unique, the waveform derived for each different character uniquely identifies that character.
In order to increase the amount of information that can be obtained when scanning the magnetically imprinted character, multiple-gap magnetic read heads have been proposed in which multiple waveforms are produced. Whereas the single-gap read head produces an analog waveform as the result of the D.C. magnetization of the channel to be read, the multiple-gap read head produces a magnetic image of the character as a result of the A.C. magnetization of the character. Problems found in using a multiple-gap read head lie in the size of the read head compared to the size of the character to be read. The read head itself consists of 30 separate tracks or channels which cover approximately 0.52 inches of the allowable MICR band. A MICR character, however, ideally spans only about 8 tracks (that is, about 0.12 inches). Therefore, every tenth channel is multiplexed together and brought out as a single channel. That is, tracks 1, 11 and 21 are tied together and brought out as channel 1, tracks 2, 12 and 22 are tied together and brought out as channel 2, and so on.
If a MICR character is positioned in the MICR band on the document such that the top of the character crosses tracks 1, 11 and 21 of the read head, then output channels 1-8 will transmit the signal with channels 9 and 10 blank. In this case, the character in each is properly oriented. If, however, the top of an MICR character crosses track 15, for example, so that it covers tracks 15 to 22, then output channel 5 will contain the top-of-character signal and output channel 2 will contain the bottom-of-character signal with channels 3 and 4 blank. In this case, the character image is said to be folded. In order to proceed with the character identification, the image must be unfolded so that it covers channels 1-8 with channels 9 and 10 blank. It is therefore an object of this invention to provide an improved method for processing data used in a character recognition system.
It is another object of this invention to improve the form of the data generated by a multi-gap read head.
It is a further object of this invention to provide that the data read by a multi-gap read head is properly oriented for use by a character recognition system in recognizing the character.